This invention relates to a manifold block for use in controlling the flow therethrough, through different channels, of a plurality of liquids having distinct physical and/or chemical properties. The block is especially suited for controlling the flow of paint delivered to a spray atomizer from a plurality of different color paint source reservoirs, which paint is applied to vehicles in the automotive industry. The manifold block is not limited, however, to the spray painting field, but will find uses in applications of other substances, viz. dyes, acids, caustics, fragrances, soaps and detergents, processing chemicals, and other, similar liquids, powder for powder coating applications or gases. Herein, the manifold block will be described with reference to paint spraying and automotive finishing, and it will be understood that the same or similar descriptions and principles of operation also apply when this manifold block is used to control the application of the aforesaid diverse substances.
In the application of paint in the automotive finishing industry, the paint may be delivered to an atomizer from a plurality of sources, each of a different color, via a bank of stackable manifolds, one of which is depicted in FIG. 1 and labeled xe2x80x9cPrior Artxe2x80x9d. This manifold will be described in detail below. Each block manifold contains at least one inlet supply line and at least one return line, per color, and the flow is controlled by a microvalve (conventional) which is triggered (controlled on-off) by an air pilot line, one per valve. The microvalves are housed within the manifold block as shown in FIGS. 1 and 2. Each color of paint recirculates into and out of the manifold until the microvalve for activation of the application of that color is triggered by the air pilot line, opening the channel to the paint applicator line leading to the paint spray atomizer. When a particular color is not being applied, the paint is allowed to recirculate continuously through the manifold to ensure that the paint will maintain its consistency, e.g., its temperature, viscosity, etc., to provide uniform flow properties throughout the application process.
In the prior, known manifold shown in FIGS. 1 and 2, the supply and return lines 52, 54 within the manifold block are connected within the block as shown, and the paint is channeled, on demand, by the microvalve 40, to and through a third channel 53, and thence to the spray atomizer (not shown) through applicator channel 38. As can be seen, when the paint is continuously recirculating through the supply and return lines, this third channel contains stagnant liquid. This xe2x80x9cdead spacexe2x80x9d within this third channel can be detrimental to the entire operation because it can cause the physical properties of the paint to degrade over time, resulting in nonuniformities and flaws in the applied coatings.
In addition, known color-change blocks generally have their paint supply and return lines, which are usually made of nylon or Teflon(copyright), attached by means of compression fittings 36. These compression fittings hold the tubings securely to the color blocks, but they can be difficult to tighten or loosen, and this is especially so when the block assemblies are housed within a robot arm, as they often are in automotive paint applications.
In addition, in these known color change blocks, the paint supply and return lines, during the application process, are often broken at the top of the compression fitting resulting from the robot maneuvering around the article being painted, which causes these lines to bend, flex and twist repeatedly. This bending and twisting causes the paint lines to break at the top of their fittings because these fittings do not allow rotation of the hoses within the fittings.
The aforesaid problems associated with the prior color block manifolds are all obviated by the manifold block of the present invention.
A manifold block for controlling the flow of liquids in various applications is provided. The block is especially suited for applying paint to vehicles in the automotive industry, but it may be used in various other applications of liquids to substrates. The manifold block houses at least one liquid inlet supply channel, at least one liquid outlet return channel, and an applicator channel in microvalved connection with the inlet channel and the outlet channel. The inlet, outlet and applicator channels meet at a common intersection in adjacent proximity to the microvalve. When the microvalve is triggered to its xe2x80x9copenxe2x80x9d position, the liquid flows through the inlet channel, to and through the applicator channel, with a portion thereof flowing to and through the outlet channel. When the microvalve is triggered to the xe2x80x9cclosedxe2x80x9d position, the liquid flows to and through the inlet channel, and to and through the outlet channel, with no liquid flow to or through the applicator channel. This operation substantially eliminates stagnation in any of the channels in either the xe2x80x9copenxe2x80x9d or xe2x80x9cclosedxe2x80x9d mode of operation of the microvalve.
The manifold block may have a plurality of paired inlet channels and outlet channels, wherein each inlet channel meets its paired outlet channel at a common microvalved intersection of these channels with the applicator channel in adjacent proximity to one of a plurality of microvalves. A preferred manifold block has two sets of paired inlet channels and outlet channels, each inlet channel meeting its paired outlet channel at a common microvalved intersection of these channels with the applicator channel in adjacent proximity to one of a pair of microvalves.
A stacked array of a plurality of the manifold blocks may be interconnected through a common applicator channel.
Preferably, the manifold block has liquid supply lines and liquid return lines connected, respectively, to the inlet channels and outlet channels by means of push fittings, and the block has incorporated therein a manually operated piston valve, channeled to interconnect the inlet, outlet and applicator channels in an operational mode, and to interconnect only the inlet and outlet channels, but isolating and closing off the applicator channel, in a nonoperational mode. This valve enables stoppage of flow to the applicator channel while simultaneously allowing recirculation of flow through the inlet and outlet channels and thus enables replacement of the microvalve with minimal disruption of operation and spillage of liquid, when configured to the nonoperational mode. The manual piston valve includes means for twisting it 90xc2x0 about its axis, to thereby transform the valve from its operational mode to its nonoperational mode.
The manifold block is useful in the application of paint to automotive vehicles and in various other coatings applications including dyestuffs, acids, caustics, fragrances, soaps, processing chemicals and similar liquids and gases.